Direct2D is literally built on top of Direct3D. There's no way around it other than either running it over the CPU (always a bad idea) or invoking some special code paths in the driver (that don't exist). Also, I don't think Direct2D is going away any time soon:
Direct2D is a user-mode library that is built using the Direct3D 10.1 API. This means that Direct2D applications benefit from hardware-accelerated rendering on modern mainstream GPUs. Hardware acceleration is also achieved on earlier Direct3D 9 hardware by using Direct3D 10-level-9 rendering. This combination provides excellent performance on graphics hardware on existing Windows PCs.
Note Starting with Windows 8, Direct2D is built using the Direct3D 11.1 API.
The reason to use Direct2D over Direct3D is a matter of convenience. If anything, D3D would be faster because you have more control over the API calls (though this is unlikely to be actually meaningful).